CVE-2026-39924: Flarum < 1.8.16 Session Persistence via Improper Access Token Revocation

Flarum before 1.8.16 contains an improper session invalidation vulnerability that allows attackers who hold a valid session token to retain full account access after a victim changes their password, because the accesstokens table is never cleared on password change events. The TokensClearer::clearPasswordTokens() function only removes rows from the passwordtokens table while leaving all active session cookies and API bearer tokens intact, including long-lived RememberAccessToken entries, and administrator-forced password resets via the user update endpoint are equally ineffective at revoking attacker-held sessions.